Rectangle
Area: ( L * W ), ( Length times width )
Perimeter: ( L + W )2, ( length plus Width and times 2 )
Square
A: ( B * H ), ( Base times high )
P: ( L * 4 ), ( Length * 4 ) or ( Length + length + length + length )
Triangle
A: ( Base times High and divided by 2 )
P: ( A + B + C), (Length + Length + Length )
Parallelogram
A: ( B * H ), ( Base times High )
Perimeter: ( L + W )2, ( length plus Width and times 2 )
(All the pictures came from Wikipedia)